1. Field of the Invention
The present invention related to a portable device and a portable timepiece including a push-in operation portion.
2. Description of the Related Art
In portable devices including timepieces such as a wrist watch and a pocket watch, a stopwatch, a cellular phone and a portable information terminal device, there are devices, for example, including an operation member such as a push bottom for operating contacts in a device outer housing, which is attached to the device outer housing. In such device, given functions are executed when the push button is pushed given times of strokes. For example, in the portable timepiece, a dial window can be illuminated, a timepiece display can be switched from an analog display to a digital display or can be inversely switched and further, the date or the day of the week which is digitally displayed can be modified.
As a shaft portion of the push button pierces the device outer housing from inside to outside in such kind of portable device, it is necessary to waterproof a portion at which the push button is formed (push-in operation portion).
In order to realize the above, a structure of waterproofing between the shaft portion of the push button and the device outer housing by fitting a seal material which has a ring shape and can be elastically deformed to the outer periphery of the shaft portion of the push button piercing a pipe fixed to the device outer housing, and allowing the seal material to be closely contacted with an inner surface of the pipe in a state where the seal material is compressed in a radial direction (refer to JP-A-2004-319446 (Patent Literature 1)).
There is also proposed a structure in which a cap covering a head portion of a push button having a shaft portion piercing an outer case from inside to outside is provided to waterproof the push button. That is, the cap is made of a flexible waterproof material, including an annular peripheral collar on an opened end side as well as including an annular lip integrally connected to the color and sectioning the opening. When a securing ring fitted to the outer periphery of the cap is fixed to the outer case by two screws, the peripheral collar is sandwiched between the securing ring and the outer case to thereby fix the cap to the outer case. This fixing allows the annular lip of the cap to abut on a bottom face of a groove formed in the outer case and to be held in a slightly compressed state, which realizes a waterproof structure (for example, refer to JP-A-2009-133859 (Patent Literature 2)).
In the waterproof structure described in Patent Literature 1, when the push button is moved in an axial direction, the seal material slides along an inner surface of the pipe. Accordingly, for example, under a condition in which the portable device is exposed to water, for example, in the case where the push button is operated in water, as the sealing performance becomes unstable because portions sealed by the seal material is moved with the push button, the waterproof performance may be reduced at a portion where the push button is arranged.
Moreover, foreign matter such as grains of sand may enter between the seal material and the inner surface of the pipe from the outside of the push button, which may be bitten between the seal material and the inner surface of the pipe. Under the above circumstances, there is a danger that waterproof property is reduced at the portion where the push button is arranged.
In the waterproof structure described in Patent Literature 2, as screws fixing the securing ring are arranged 180 degrees apart from each other around the cap, it is difficult to sufficiently secure a force of sandwiching the peripheral collar at positions 90 degrees apart from these two screws in a circumferential direction of the cap, therefore, water may climb over the peripheral collar and enter the annular lip side in water and other places. Therefore, when the cap is elastically deformed in water and the push button covered by the cap is operated, there is a danger that the waterproof property is reduced. That is, as the cap is pressed in water, the pressing force to be affected on the annular lip may move the annular lip with deformation. As a result, as the waterproof performance due to the annular lip becomes unstable, there is a danger that the waterproof property is reduced.
Furthermore, in the waterproof structure described in Patent Literature 2, the waterproof structure is realized by using the cap, the securing ring and two screws. Accordingly, the number of components for the waterproof structure is large and the structure is complicated, therefore, the number of assembly processes for the waterproofing is also large as well as the number of processes with respect to the outer case which are necessary for screwing the securing ring is also large. Accordingly, it is disadvantageous on reducing costs.
The related art techniques have problems that there is room for improvement on the waterproof performance around the push button as well as there is room for improvement on simplifying the structure and reducing costs.